June 5, 2006

Sunesis Pharmaceuticals has reported promising clinical data from two Phase I studies evaluating once-weekly and once-every-three-week dosing schedules of SNS-595 in patients with advanced solid malignancies. In both trials, SNS-595 exhibited clinical activity across a variety of tumor types among end-stage refractory patient populations and was well-tolerated with manageable side effects.

Out of a total of 62 evaluable patients from both Phase I studies, two patients achieved partial responses, another 17 patients achieved stable disease for fifteen weeks or greater, with one patient maintaining stable disease for more than a year. Patients enrolled in both studies had advanced disease in a variety of tumor types including ovarian, lung, colon, pancreatic and renal. All had previously progressive disease at the time of enrollment despite prior treatments. SNS-595 was well tolerated, with a dose-limiting toxicity of reversible non-cumulative neutropenia. In addition, SNS-595 demonstrated consistent and predictable pharmacokinetics across both dosing regimens.